Fig. 3: Population structure and island formation.

a Individual admixture proportions for 180 individuals, 9223 neutral SNPs and K = 3 ancestral populations and b individual admixture proportions for 56 individuals, 9223 neutral SNPs and K = 4 ancestral populations, ordered from left to right following sequential island separation. c Hypothetical paleogeographic formation of the Galapagos archipelago with sequential separation of Española Island (purple) at 2–1.5 million years ago (Mya), San Cristóbal Island (green) at 1.5–1 Mya, and Floreana Island (yellow) at 1–0.5 Mya, and the emergence of individual islands that formed Isabela and Fernandina Islands since 0.5 Mya, adapted from (Karnauskas et al. 2017). d Present day Galapagos with 210 m isobath indicating the land area that was exposed at the lowest sea level during the last 700,000 years.